1. Field of the Invention
The present invention relates to an optical wireless communication system in which a central device controls a plurality of parent devices and each of the parent devices communicate with a plurality of child devices in one of the sections into which the whole communication area is divided.
2. Description of the Prior Art
This kind of optical wireless communication systems requires separation of communications among the sections in the communication area. That is, a communication between a parent device and each of the child devices in each section has to be achieved without interfering any devices in other (or adjacent) sections or being interfered by any devices in other (or adjacent) sections.
For this purpose, there may be devised some measures in which screens are provided at the boundaries between sections so as to prevent a communication light in each section from leaking into adjacent sections, or spaces are left between sections so as to cause a communication light in each section not to reach adjacent sections. However, these measures would spoil an advantage or setting-up easiness of optical wireless communication systems.
For this reason, different radio carriers (frequencies) are allocated to adjacent sections in the communication area in order to separate adjacent sections from each other. In this case, each of both the parent devices and the child devices requires a filters for extracting a radio carrier allocated thereto. The filter has to be such as has a selectivity of more that a certain level because signals from other sections that have not been filtered off by the filter would interfere with a communication within the section. However, such filters as have high selectivity are expensive causing the cost of the while system to be high.
Therefore, it is an object of the invention to provide an optical wireless communication system and method which permits sure separation of communications among the sections in the communication area.